Sterilization unit for a filling machine

ABSTRACT

A sterilization unit comprises at least one nozzle pipe for injection of a sterilization agent into a packaging container to be sterilized. The sterilization unit is driven to move in an axial direction, in a downward stroke and an upward stroke, corresponding to a longitudinal direction of the nozzle pipe such that it is inserted into an open end of the packaging container during sterilization thereof. The nozzle pipe is suspended such as to be displaceable in relation to the sterilization unit, in the axial direction.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a divisional application of U.S. patent applicationSer. No. 14/372,630 filed on Jul. 16, 2014, which is a U.S. NationalStage application of International Patent Application No.PCT/EP2013/050360 filed on Jan. 10, 2013, which claims priority toSwedish Patent Application No. 1250020-3 filed on Jan. 16, 2012, theentire contents of all three of which are incorporated herein byreference.

FIELD OF THE INVENTION

The present invention relates to an arrangement in a filling machineutilized for filling of liquid foodstuff into packaging containers. Inparticular it relates to an arrangement in a sterilization section ofsuch filling machine.

BACKGROUND

Before filling packaging containers with liquid foodstuff it is commonto perform a sterilization procedure, in which a liquid or vaporizedsterilization agent is injected into the interior of the packagingcontainer in order to eliminate any microorganisms present.

Within the field of the present applicant the packaging container isformed from a laminated material comprising layers of paper andthermoplastic material. The choice of thermoplastic material as well asthe presence of any further layers, such as aluminium foil or othermetal foil, or additional barrier layers, will depend on the type ofproduct to be contained and the desired shelf-life for such product. Aminimum criterion is that the interior of the packaging container shouldnot absorb moisture to the extent that the integrity of the packagingcontainer is jeopardized. In most cases the same is true for theoutside. Further barrier layers, of which aluminium foil is one example,may be arranged to prevent light or oxygen from diffusing into thepackaging container after it has been sealed. Such measures may bedesired in instances where an extended shelf-life is desired. Whilethese measures relate to what can be done in order to maintain theconditions after a packaging container is filled and sealed, the presentinvention is closer related to the measures performed in order to obtainproper conditions prior to filling of the container.

An example is disclosed in the publication EP-1 046 585 by the presentapplicant, which should be sufficient in order for the skilled person tograsp the background and aid in realization of the beneficial featuresof the present invention.

SUMMARY

The present invention concerns a sterilization unit for a fillingmachine. The sterilization unit comprises at least one nozzle pipe forinjection of a sterilization agent into a packaging container to besterilized, and the sterilization unit is driven to move in an axialdirection, in a downward stroke and an upward stroke, corresponding to alongitudinal direction of the nozzle pipe such that it is inserted intoan open end of the packaging container during sterilization thereof. Thesterilization device is characterized in that the nozzle pipe issuspended such as to be displaceable in relation to the sterilizationunit, in the axial direction.

The advantage of having a displaceable suspension will be evident fromthe detailed description. It should be emphasized that “downward stroke”and “upward stroke” refers to the expected direction in a fillingmachine where a package is sterilized from an open end directed upwards,through which it is subsequently filled with contents. This alsocorresponds to the direction in the embodiment shown in the detaileddescription. In that respect “downward” and “upward” could be replacedby “outward” and “inward”, “forward” and “backward” or another pair ofopposing directions in case the packages does not have a verticalorientation and are being sterilized from above.

To further increase the killing efficiency the sterilization unit maycomprise a plate provided with holes allowing passage of the nozzle pipeduring sterilization. The plate should preferably cover the extension ofthe open end of the packaging containers, and it may also beadvantageous if a single plate covers all packaging containers currentlyprocessed in the sterilization unit. The plate will maintain thesterilization agent in the interior of the packaging container to ahigher extent, and sterilization agent leaving the interior of thepackaging container will also to a higher extent be directed downwardswhere it may have a sterilization effect on the outside of the packagingcontainer, and at least on an upper region thereof. In an embodimentwhere the plate is static it will be arranged such that there is aclearance between a lower edge of the plate and the uppermost end of thepackages, to allow passage of the packages. In an embodiment where theplate is moveable to some extent together with the sterilization unitsuch clearance may be even smaller or non-existing after the packageshave been indexed to the correct position.

In one or more embodiments the nozzle pipe may have a length exceedingthe length of a single stroke of the sterilization unit. This will befurther described in the detailed description of the presentapplication. It is preferred that the nozzle pipe is rectilinear alongthis length.

In one or several embodiments the nozzle pipe has a constant crosssection over at least a length corresponding to the length of a singlestroke of the sterilization unit, such that it may move freely whenneeded.

In another embodiment the suspension of the nozzle pipe is provided by asleeve with a through hole in the axial direction, the sleeve beingrigidly attached to the sterilization unit. The use of a sleeve is oneof the simpler, and still preferred, embodiments of the presentinvention. The sleeve may or may not apply a clamping force onto thenozzle pipe, and if such a clamping force is to be applied it may beeffected by the sleeve being resilient or by the intermediate of someresilient means, such as a spring or an o-ring between the sleeve andthe nozzle pipe.

In a related embodiment the nozzle pipe is provided with a section ofextended diameter remote to its free end. The section of extendeddiameter will enable the sleeve to locate the nozzle pipe in one of theaxial directions, i.e. prevent it from falling downwards into thepackaging container, in a very simple manner. The section of extendeddiameter may be provided by a coupling which fluidly connects the nozzlepipe with a flexible line through which the sterilization agent isdelivered, meaning that the number of components used is kept low.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematical side view of the sterilization section of afilling machine, including an embodiment of the present invention in afirst operational state.

FIG. 2 is a schematical side view of the embodiment of FIG. 1 yet in asecond operational state.

DETAILED DESCRIPTION OF EMBODIMENTS

The present invention will now be described by virtue of an embodimentthereof. FIG. 1 illustrates a segment of a filling machine, and inparticular a sterilization section thereof. It should be emphasized thatthe drawing is schematic only, individual components does notnecessarily have the illustrated design, since the detailed design isnot relevant for the functional description of the invention, whichstill will be detailed enough for the skilled person to be able to workthe invention. In the present context “sterilization” and similar termsshould be construed as providing a sterilization agent to a packagingcontainer, rather than a quantitative measure of the actual effect ofthe act.

Starting with the general flow, packaging containers 102 follow amachine direction from left to right (referring to FIG. 1). They areindexed two positions between processing activities, which isillustrated by the brackets provided with roman numerals (I, II, andIII). Prior to entering the illustrated section of the filling machinethe containers 102 have been formed and provided with a closed end, nowfacing downwards. The closed end may be accomplished by sealing andfolding one end of a tubular sleeve of packaging material, yet it mayalso be accomplished by providing one end of the tubular sleeve ofmaterial with a top of an alternative material, such as plastic, whichwas described in the summary. In the is context “sleeve” should includea tubular shape with any cross section, such as rectangular, oval,prismatic etc, wherein the cross section may vary along the extension ofthe tubular shape. The invention as such is found in processing step II,though embodiments of the invention may also incorporate procedures andelements from neighbouring processing steps.

The material of the sleeve includes a laminated material comprisinglayers of paper and thermoplastic material. In the preferred embodimentaluminium foil or other metal foil is added as a further barrier layer,yet other barrier layers may be used instead or in combination with thealuminium layer. The specific composition of the packaging material ishowever not directly relevant for the understanding of the presentinvention, however important it may be for the shelf life of a resultingpackaging container filled with content.

In a first processing step I the packaging containers 102 are subjectedto a first treatment with vaporized hydrogen peroxide, and followingthat first treatment the packaging containers 102 are indexed to stepsforward to the second processing step II where they are again subjectedto a treatment with vaporized hydrogen peroxide. The hydrogen peroxideis provided to the packages via nozzle pipes 114, 120, 122 in thisembodiment, two for each processing step. The hydrogen peroxide (or analternative sterilization agent) may in turn be supplied to the nozzlepipes from a supply via flexible tubes connected to one end of thenozzle pipes.

In the first processing step I the layout is the following: asterilization unit 104 has a nozzle pipe 114 extending in a verticaldirection (coaxial with a longitudinal direction of the packagingcontainer 102). The nozzle pipe is in fluid connection with a source ofvaporized hydrogen peroxide, of which there are several alternatives inprior art. When sterilizing the packaging container 102 the nozzle pipe114, or rather the entire sterilization unit 104 including the nozzlepipe, 114, is lowered so that the nozzle pipe 114 enters the container102 where it injects the hydrogen peroxide. Following the injection thesterilization unit is retracted upwards to its first position, and hasthen performed a downward stroke and an upward stroke of identicalstroke length. Injection of hydrogen peroxide (or another sterilizationagent for that matter) may occur both on the travel downwards and thetravel upwards and when the sterilization unit is in its lowermostposition, or in any selection of these transitions or positions.

The movement of the sterilization unit may be accomplished e.g. by meansof a servomotor synchronized with the indexing of the packages, or by adrive connected to a main drive of the filling machine. The choice ofdrive is not crucial for the understanding of the present invention.

In the specific embodiment described this first processing step Iincludes a prefolding and forming step. The packaging container inquestion may be a so called gable-top package, and the prefoldingfacilitates adequate folding and sealing in the steps following thesterilization section. For this purpose the sterilization unit 104 isprovided with a forming tool 118 which is suspended in rails or rods 116and which may move independently from the rest of the sterilization unit104, at least in the directions of the rails 116. Further forming tools(not shown) are present in the first processing step, yet a detaileddescription of these would obscure the invention in question. The secondsterilization unit 106 used in the first processing step is of identicaldesign and a detailed description is therefore considered superfluous.

In processing step III the packages 102, now having a layer of condensedhydrogen peroxide coating all inner surfaces, will be subjected toultraviolet radiation to enhance the killing of microorganisms. Thecombination of hydrogen peroxide and ultraviolet radiation is consideredto be an established sterilization technique. To protect an operator theradiation treatment is performed in a confined area surrounded by ashield construction as indicated by the dashed frame. The entire processas described herein is performed in a controlled atmosphere such thatthe sterilization performed is not compromised by reinfection at anotherstage. In or subsequent to processing step III a stream of hot air maybe injected into the containers to remove any residual sterilizationagent which otherwise may result in an off taste of a product containedtherein.

In order to improve the killing of microorganisms the packages 102 aresubjected to a second injection of hydrogen peroxide by means of asterilisation unit 108 (and 110). This sterilization unit does notinclude a forming tool, but it does include a shield in the form of ashielding plate 124, effectively forming a roof above the containers102. The plate or shield 124 has a dual purpose in that it prevents e.g.particles from falling into the container 102 from above, while at thesame time confining the injected hydrogen peroxide inside the container102 after injection. Even further, hydrogen peroxide being injected intoa container will be redirected downwards (at least to a higher extent)as it leaves the open end of the container 102, which will ensuresterilization of the upper portion of the container outside, thuspreventing reinfection to a higher extent. The relative statement “to ahigher extent” refers to a configuration without a shield 124. The plate124 may preferably cover all packaging containers presently locatedbelow the sterilization units 108/110 of the second sterilization step,since this may prevent any debris from falling into a packagingcontainer.

Holes (not visible in the side view of FIGS. 1 and 2) are arranged inthe shield 124 for allowing passage of the nozzle pipes 120, 122. Inorder for the holes to affect the performance and purpose of the shieldto as little extent as possible, the holes should be as small aspossible. This is turn implies that the diameter of the pipes 120, 122should be small, and since they still have to deliver a certain amountof sterilization agent the pipe walls will be thin, and the pipes assuch will consequently be quite fragile. The holes are preferablycircular since the pipes generally have a circular cross section,however both the holes and the pipes may have other shapes. The holesmay also have an extension in the axial direction, so as to provide amore efficient gas lock, i.e. to increase the fluid resistance for afluid wanting to flow in a clearance between an outer perimeter of thepipe and the inner perimeter of the hole.

The second sterilization unit is operationally attached to the firststerilization unit and they move synchronously, in the describedembodiments both sterilization units are operationally connected to thesame frame 112. More elaborate solutions may be used yet the simplicityof the present solution is preferred. The sterilization unit acceleratesrapidly and at an elevated frequency since thousands of packages aretreated every hour. For this reason, and in combination with thefragility of the nozzle pipes 120, 122, the nozzle pipe may oscillateslightly during operation. Due to the tight fit between the holes andthe outer diameter of the nozzle pipe such oscillations couldpotentially result in that the nozzle pipe misses the hole ever soslightly. In such a case the sterilization unit will continue to movedownwards, and the pipe 120 or 122 will be severely deformed. Anotherscenario is that the volume below the hole is blocked, e.g. by a faultypackaging container. Such an event may also destroy the nozzle pipe. Adirect measure to take would be to increase the diameter of the hole,add guides and/or to reinforce the nozzle pipe in one of many ways.

According to the present invention each of the nozzle pipes 120 and 122are positioned by a sleeve 126 and 128 respectively, see FIG. 2. Eachsleeve 126, 128 comprises a through opening (not shown) which locatesthe corresponding pipe 120, 122 firmly, while leaving it movable in anaxial direction, i.e. in a longitudinal direction of the nozzle pipe. Inthe event of the nozzle pipe missing the hole the nozzle pipe 122 willbe axially displaced in the sleeve 128, thus preventing irreparabledamage of the nozzle pipe. Having said this, it should be emphasizedthat the displaceable arrangement of the nozzle pipes may be used evenif there is no plate 124, since blockages of various types may occur.Also, it may be noted that there obviously are more elaborate ways ofarranging the nozzle pipe 120, 122 to be movable or displaceable, suchas e.g. a suspension comprising a linkage or a telescopic arrangement,such as a rod and piston arrangement.

In FIG. 2 it is schematically illustrated how the pipe 122 has beendisplaced in the sleeve 128, while the other pipes and forming toolshave engaged a corresponding package. For the purposes of the presentinvention it is beneficial if the nozzle pipe 122 has a length exceedingthe stroke length of the sterilization unit, at least in the simpleembodiment where the suspension comprises a sleeve locating the nozzlepipe 122. This will reduce the risk of the pipe nozzle 122 (or 120 forthat matter) being forced out of the suspension. In the same and otherembodiments it is beneficial if the nozzle pipe has a constant crosssection, at least over the stroke length, such that a firm positioningis obtained as the nozzle pipe is displaced in relation to thesterilization unit. Components described in relation to FIG. 1 andhidden inside the container in the view of FIG. 2 are shown in dottedlines in FIG. 2.

In FIG. 2 it is also visualized how the forming tools 118 have performeda relative movement in relation to the rest of the sterilization unit,upwards along the rails 116. In a real installation there are otherforming tools performing actions onto the packaging container, whichforming tools are not shown in FIG. 2. Movement of the forming tools 118and the tools not shown may be performed by the same drive as the drivemoving the sterilization unit and the relative movement may be realizedby a cam or link system. In the case of the forming tools 118 thesolution may be even simpler. With the forming tools being movable alongthe rails 116 and resiliently biased downwards a physical block limitingthe downwards movement of the forming tools 118 as the sterilizationunit moves downwards may suffice. Even if specific solutions may beinventive the general concept is well known and a skilled person mayreadily come up with alternative solutions and the construction will notbe discussed further within the context of the present invention andembodiments thereof.

Each sterilization unit comprises two pipes or nozzles in the disclosedembodiment. The skilled person realizes that in an embodiment where thepackaging containers are indexed a different number of steps, therewould also be a different number of nozzles or pipes in each unit, suchas one, three, four etc.

Further to this rudimentary embodiment the sterilization unit maycomprise a biasing device (not shown), biasing each nozzle pipedownwards, such that the nozzle pipe is automatically repositioned afteran accident. A position sensor (not shown) may also be arranged in thefilling machine. The position sensor may comprise a photocell device, acontact-breaker device, a pressure sensor or any suitable sensor whichmay provide an output signal in a situation where a nozzle pipe isdisplaced. A response to the sensor output may be that the package inquestion is marked or made possible to track so that it may be easilydiscarded at a later stage of the processing downstream thesterilization (since the sterilization may be incomplete). Anotherresponse may be that the machine operation is halted such that any causeof error may be removed before inducing damage to the sterilization unitor the machine.

The present invention is particularly well adapted for use insterilization of packaging containers being formed from blanks ofpackaging material (of the type previously described) formed from alaminate comprising a paper core surrounded by laminated layers ofthermoplastic material, and potentially further layers such as analuminium foil (or other metal foil) for improving the oxygen-barrierproperties. The blank is shaped by bending and folding to form a sleeve,the longitudinal edges are joined, and the thus formed sleeve is closedat one end, so as to form a packaging container with an open end. Theclosing of the one end may be performed by sealing and folding of thesleeve as such, yet it may also be performed by moulding a top ofthermoplastic material to the one end of the sleeve. Both theseapproaches will result in commercially available types of packagingcontainers, commonly referred to as “carton bottles” and “gable tops”,respectively. The first steps in the forming process may be performedbefore the actual filling machine, such that the packaging container tobe is provided to the filling machine as a flattened sleeve, as may bethe case for a gable top, or in any intermediate form, such as aflattened rectangular blank, as may be the case for a carton bottle. Thepackaging material may also be provided to the filling machine in theform of a continuous web of packaging material, which is cut into blanksin a section of the actual filling machine, also an example which may beused for carton bottles. In each of these cases the resulting packagingcontainer will be sterilized and filled from an open end thereof, whichend subsequently will be sealed and folded, as oppose to a situationwhere the package container is sterilized and filled via a spout laterto be provided with an opening device.

The invention claimed is:
 1. A method of operating a sterilization unitfor a filling machine, the sterilization unit comprising a frame movablein an axial direction and first and second nozzle pipes for injectingsterilization agent, the first and second nozzle pipes being movabletogether with the frame in the axial direction to position each of thefirst and second nozzle pipes in an interior of a respective one ofpackaging containers to deliver sterilization agent to the interior ofthe respective packaging container, the method comprising: verticallymoving the frame downward along the axial direction toward upwardly openends of the packaging containers, the downward movement of the framealso downwardly moving the first and second nozzle pipes, the firstnozzle pipe contacting an obstruction during the downward movementtoward the upwardly open ends of the packaging containers so thatfurther downward movement of the first nozzle pipe is stopped;continuing the downward movement of the frame and the second nozzle pipewhen the first nozzle pipe contacts the obstruction and stops thedownward movement of the first nozzle pipe, so that the second nozzlepipe passes through the upwardly open end of a corresponding one of thepackaging containers and is positioned in the corresponding packagingcontainer; and injecting sterilization agent from the second nozzle pipeinto the corresponding packaging container.
 2. A method comprising:vertically moving a frame downward toward upwardly open ends ofpackaging containers, the downward movement of the frame also downwardlymoving first and second nozzle pipes as well as first and secondsleeves, the first nozzle pipe being positioned inside the first sleeveand the second nozzle pipe being positioned inside the second sleeve;stopping downward movement of the first nozzle pipe as a result of thefirst nozzle pipe contacting an obstruction during the downward movementtoward the upwardly open ends of the packaging containers; continuingthe downward movement of the frame, the first sleeve, the second nozzlepipe and the second sleeve when the first nozzle pipe contacts theobstruction and stops the downward movement of the first nozzle pipe, sothat the second nozzle pipe passes through the upwardly open end of arespective one of the packaging containers and is positioned in therespective packaging container; and injecting sterilization agent fromthe second nozzle pipe into the respective packaging container.
 3. Themethod of claim 2, wherein at least some of the sterilization agent isinjected from the second nozzle pipe into the respective packagingcontainer during downward movement of the second nozzle pipe.
 4. Themethod of claim 2, wherein at least some of the sterilization agent isinjected from the second nozzle pipe into the respective packagingcontainer during upward movement of the second nozzle pipe afterdownward movement of the second nozzle pipe.
 5. The method of claim 2,wherein at least some of the sterilization agent is injected from thesecond nozzle pipe into the respective packaging container during a timebetween downward movement of the second nozzle pipe and subsequentupward movement of the second nozzle pipe.
 6. The method of claim 2,wherein the sterilization agent includes hydrogen peroxide.
 7. Themethod of claim 2, wherein the respective packaging container possessesinner surfaces, and the method further comprises covering all innersurfaces of the packaging container with at least some of thesterilization agent.
 8. The method of claim 7, further comprisingsubjecting the respective packaging container to ultraviolet radiationafter injecting the sterilization agent from the second nozzle pipe intothe respective packaging container.
 9. The method of claim 8, furthercomprising subjecting the respective packaging container to a stream ofheated air after subjecting the respective packaging container toultraviolet radiation.
 10. The method of claim 2, further comprising:passing the second nozzle pipe through a hole in a shield or platepositioned vertically below the second nozzle pipe, during downwardmovement of the second nozzle pipe before injecting sterilization agentfrom the second nozzle pipe into the respective packaging container; andredirecting at least some of the sterilization agent into the respectivepackaging container using the shield or plate.
 11. A method comprising:vertically moving a frame downward toward upwardly open ends of firstand second packaging containers, the downward movement of the frame alsodownwardly moving a first nozzle pipe configured to inject sterilizationagent in the first packaging container and a second nozzle pipeconfigured to inject sterilization agent in the second packagingcontainer; the first nozzle pipe contacting an obstruction during thedownward movement toward the upwardly open end of the first packagingcontainer so that further downward movement of the first nozzle pipe isstopped; and continuing the downward movement of the frame and thesecond nozzle pipe when the first nozzle pipe contacts the obstructionand stops the downward movement of the first nozzle pipe, so that thesecond nozzle pipe passes through the upwardly open end of the secondpackaging container and is positioned in the second packaging container.12. The method of claim 11, further comprising injecting sterilizationagent from the second nozzle pipe into the second packaging container.13. The method of claim 12, wherein at least some of the sterilizationagent is injected from the second nozzle pipe into the second packagingcontainer during downward movement of the second nozzle pipe.
 14. Themethod of claim 12, wherein at least some of the sterilization agent isinjected from the second nozzle pipe into the second packaging containerduring upward movement of the second nozzle pipe after downward movementof the second nozzle pipe.
 15. The method of claim 12, wherein at leastsome of the sterilization agent is injected from the second nozzle pipeinto the second packaging container during a time between downwardmovement of the second nozzle pipe and subsequent upward movement of thesecond nozzle pipe.
 16. The method of claim 12, wherein thesterilization agent includes hydrogen peroxide.
 17. The method of claim12, wherein the second packaging container possesses inner surfaces, andthe method further comprises covering all inner surfaces of the secondpackaging container with at least some of the sterilization agent. 18.The method of claim 17, further comprising subjecting the secondpackaging container to ultraviolet radiation after injecting thesterilization agent from the second nozzle pipe into the secondpackaging container.
 19. The method of claim 18, further comprisingsubjecting the second packaging container to a stream of heated airafter subjecting the second packaging container to ultravioletradiation.
 20. The method of claim 11, further comprising: passing thesecond nozzle pipe through a hole in a shield or plate positionedvertically below the second nozzle pipe, during downward movement of thesecond nozzle pipe; injecting sterilization agent from the second nozzlepipe into the respective second packaging container; and redirecting atleast some of the sterilization agent into the respective secondpackaging container using the shield or plate.
 21. The method of claim11, wherein the vertically moving of the frame downward occurs during afirst downward movement stroke of the frame, and the packagingcontainers are a first set of packaging containers, the method furthercomprising vertically moving the frame downward along the axialdirection toward upwardly open ends of a second set of packagingcontainers during a second downward movement stroke of the frame toposition the first nozzle pipe in one of the packaging containers of thesecond set of packaging containers without contacting an obstruction andto position the second nozzle pipe in another one of the packagingcontainers of the second set of packaging containers without contactingan obstruction.